Hi Robert,
Thanks for your response. At least I have an excuse to tell the students why occasionally the Ethernet doesn’t work
We don’t have students log in over serial, because then each student would need to purchase a USB-to-serial adaptor to connect to their laptop. (Also as far as I know, there is no straight-forward way to forward X-windows over that kind of connection in a way that is easily compatible with Mac OS, Windows, and Linux laptops.)
Originally, we used the USB over Ethernet feature for the Beagle Board original, but I found that every time I plugged it into my OS X laptop, it came up as a new device name, which was really inconvenient because I had to input the settings each time, and then I wound up will all of these old interfaces that I had to manually delete one after another. (I realize there could possible be an easy way to fix this on OS X, but I started thinking that maybe not very many people used this kind of connection, so maybe it would be a hassle to get it working under Windows and Linux as well. Students bring in all sorts of different kinds of laptops – the worst are these netbooks with crippled versions of Windows, for which the feature for sharing a wireless Internet connection with the Ethernet port is disabled.)
So that is why we are using the Ethernet connection. It has become quite standard by now, so at least it seems to be relatively easy to setup. (The worst thing is that Windows users have to install Cygwin, which takes quite a while depending on which packages they install. Because of that we ask Windows users to install Cygwin before coming to the first class.)
Anyway of course your solution works for getting the Ethernet up and going again (I usually instead resort to just unplugging and replugging the Ethernet cable until the lights on the Ethernet port come on), but this is confusing for beginning students, and since they are only connected by Ethernet, they can’t run that command if they’re not plugged in. (A while ago I tried running “sudo ifdown eth0; sleep 5; sudo ifup eth0” on boot, but of course the Ethernet can always fail to come up upon the manually-setup ifup, even if it already came up the first time after all.
Finally, I just purchased a 3A 5V power supply (DVE DSA-0151F-05) to see if this helps, but I can only verify that this does not make the Ethernet connection come up reliably. There is no easily measurable improvement for me.
uname -a
Linux omap 3.2.2-x4 #1 SMP PREEMPT Wed Feb 15 07:09:50 PST 2012 armv7l GNU/Linux
Cheers,
Edgar